Of course, there is no denying that the realization of space solar power station is an extremely huge and arduous space activity. It needs to construct a huge object the size of a small town in space. Needless to say, Su is facing serious challenges in engineering alone.
The first is energy conversion. The solar panel structure of the power station is huge, with a total weight of 12400 tons. The diameter of the central rotating shaft is 100 meters, and the rotation should be very stable and accurate. It is unimaginable to build such a large component on the ground. It can only be processed and manufactured in a space factory. According to the calculation, the number of solar cells needs 14 billion! Therefore, the key to the success or failure of the power station is to solve the production capacity of solar cells and huge production costs. Over the past five years, the United States has stepped up research on the production technology of monocrystalline silicon and polycrystalline silicon, trying to meet the requirements of power stations as soon as possible. In addition, the space production of solar cells is also under active research. Once this technology is realized, it will pave the way for the establishment of power stations.
The second is the problem of microwave transmission in energy space. Millions of high-power microwave tubes are used to convert the DC power generated by the solar cell panel into microwave power. However, at present, the production capacity of the United States can basically meet the requirements of building power stations, which is of course optimistic. However, in this link, the manufacturing problems of transmitting antenna and ground receiving antenna need to be solved.
The transmitting antenna is a circular phased array antenna with a diameter of 1 km. The sub array surface of the antenna is 20 square meters, and the direction of the antenna should be very accurate. This kind of antenna is currently in the demonstration stage, and there is still a long way to go before it is put into production.
The ground receiving antenna is also unusual. It is a dipole antenna array with a length of 14 kilometers and a width of 10 kilometers. The received microwave is rectified by special equipment and then put into the power grid. The simulation experiments that have been done show that the receiving and rectification efficiency is 82%.
The third is space production and orbital transportation. NASA and Grumman have studied two power station assembly methods. The first is low orbit assembly, that is, a space factory with about 700 people will be established in the low orbit. Truss structures and solar cells will be produced and assembled in this factory. After the assembly of the whole power station, it will be sent to the geostationary orbit by electric propulsion system. The second is the geostationary orbit assembly method. This requires the factory to be located in the geostationary orbit, and the personnel and equipment will be transferred to the geostationary orbit factory through the low orbit, and finally manufactured and assembled there. Both schemes are in the experiment. Once the experiment is successful, another big obstacle will be removed.
A solar power station needs about 100000 tons of building materials and hundreds of space operators. How can we send so many people and materials to space? According to the two assembly methods described above, different vehicles will be used respectively. For the low orbit scheme, it was envisaged in the early stage to transport by single-stage rocket and space shuttle, with a carrying capacity of 70 ~ 200 tons. Now imagine a winged aircraft propelled by a two-stage rocket - a space transport ship. Its take-off weight is 11000 tons, and its carrying capacity is considerable. A large number of materials ranging from 4000 to 4500 tons can be delivered to the construction site each time. According to this calculation, the space transport ship can transport all the equipment for building a power station as long as it makes about 22 trips. In the stage of transferring from low orbit to high orbit, the orbital transport ship working with ion rocket engine or chemical propellant will be used.
To sum up, although there are still many problems to be solved in the establishment of solar power plants, it can be said with full confidence that the prospect is bright. According to NASA's plan, at present, the assembly method is mainly tested on the ground, and an experimental power generation satellite will be launched at the later stage of this stage; The second stage is to launch a sample star with a power generation capacity of 200000 ~ 500000 kW, which is expected to be completed in the near future; The third stage is the full implementation stage. It is planned to build a 5 million KW satellite power station by 2014, and it will break through 100 hurdles by 2050. C.R. Woodcock, head of Boeing's research department, predicted optimistically: "in the distant future, there will be hundreds of satellite power stations around the earth to meet human energy requirements."
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